Biomass, in particular biomass of plant origin, is recognized as an abundant potential source of fuels and specialty chemicals. See, for example, “Energy production from biomass,” by P. McKendry—Bioresource Technology 83 (2002) p 37-46 and “Coordinated development of leading biomass pretreatment technologies” by Wyman et al., Bioresource Technology 96 (2005) 1959-1966. Refined biomass feedstock, such as vegetable oils, starches, and sugars, can be substantially converted to liquid fuels including biodiesel (e.g., methyl or ethyl esters of fatty acids) and ethanol. However, using refined biomass feedstock for fuels and specialty chemicals can divert food sources from animal and human consumption, raising financial and ethical issues.
Alternatively, inedible biomass can be used to produce liquid fuels and specialty chemicals. Examples of inedible biomass include agricultural waste (such as bagasse, straw, corn stover, corn husks, and the like) and specifically grown energy crops (like switch grass and saw grass). Other examples include trees, forestry waste, such as wood chips and saw dust from logging operations, or waste from paper and/or paper mills. In addition, aquacultural sources of biomass, such as algae, are also potential feedstocks for producing fuels and chemicals.
When biomass materials are subjected to thermal treatment, like in typical pyrolysis processes, the liquids/vapors generated comprise mostly large aromatic and poly nuclear aromatic molecules, which are directly released from the biomass as it is thermally decomposed. Additional polynuclear aromatic molecules can be formed from cross interactions of the nascent molecules at the biomass/vapor interface and in the vapor phase. It is known that long residence times as well as large biomass particles enhance these side reactions and the fuel oil products produced contain larger molecules at a given thermolysis operating reactor temperature. To that effect, the operating parameters need to be optimized for a given kind of biomass material to obtain the maximum oil yield, minimum liquid hydrocarbon oxygen content, and minimum gas and coke yields.
There is a need to develop cost-effective catalyst to be used during the thermolysis process in order to catalytically crack some of the large molecules to lighter ones and at the same time cause an optimum deoxygenation so that the liquid oil will contain light molecules and less overall oxygen.